The synthesis and application of nanoparticles, i.e., particles smaller than one micron, are of growing interest to both industry and academia. Nanocapsules, a particular type of nanoparticles, are composed of one or more active materials (core) and a protective matrix (shell). (1) Encapsulation technology has been used to prepare micro/nanocapsules with specific application properties in many areas including food (2), biology (3), and medicine (4).
Nanocapsules have been synthesized via miniemulsion (5,6) and interfacial polymerization (7,8) techniques. Couvreur reviewed nanocapsule technologies used in drug carrier systems.(9) To date, isocyanates have generally been used to form shell (or matrix) materials for encapsulating functional materials, releasable fill materials, (10) or making pressure sensitive copying paper (11). However, the inherent reactivity of isocyanates with water makes it difficult to encapsulate them in aqueous media.